No one can ever use his heart to listen or touch or feel or see or smell. It's just a lump of muscle pumping mechanically inside your ribs. It has no will and no ability to do anything but go on pumping until it gives up and withers away or is choked by some disease. Your spinal cord, on the other hand, feels. The central nervous system pours out from the spinal cord, and with it one feels pain. Pain is the most trustworthy sensation a human being can know because it teaches us what hurts. With the spinal cord, one can hear what will hurt, smell the sting of suffering, taste it, feel it, and see the world with new eyes. I learned a long time ago not to follow my heart, the hunk of meat flexing in the chest. I trust the tube locked up in a column of bone, the tube that shows me what pain is.
